Launching gear for boats



W. E. MORLEY ETAL LAUNCHING GEAR FOR BOATS April 21,1953

3 Sheets-Sheet l Filed Jan. 20, 1948 April 21, 1953 w. E. MORLEY ETAL2,635,259

LAUNCHING GEAR FOR 'BOATS Filed Jan. 20, 1948 3 Sheets-Sheet 5 y W.Allo/nay Patented Apr. 2l, 1953 LAUNCHING GEAR FORBOAT William EdwardMorley, Gillingham, Walter Gordon Moore, Brkdale, and William CameronRouse, Liverpool, England applicati@ January zo, 194s, serialN. 3,346 InGreat Britain January 27, 1947 1 claim. 1

This invention is for improvements in or relating to launching and lowergear (e. g. lowering gear for ships lifeboats) of the gravity-operatedtype comprising a davit arm or the like and a stand and having amultiple pivot arrangement for the davit arm (i. e. of the type in whichthere are at least two pivots about which the davit armswings outboardsuccessively). Such launching or lowering gear is hereinafter referredto as a davitof the type specied.

One object of thepresent invention is to provide a davit or the like ofthe type specied, in which movement of the davit arm is checked orguided so that the davit head or horn follows a relatively smooth path.In other words. an object of the present invention is to smooth out thestep or steps, and thereby the abrupt changes of load which occur inmultiple pivot davits as the arm changes from one pivot to another.

Accordingly the present invention provides a gravity davit of the typespecified and having, at least, two pivots about which the davit armpivots outboard successively, characterised by guide means acting on thedavit arm to guide it out of trulyeircular movement about, at least, therst of said pivots and reduce the curvature of the path of movement ofthe davit arm head to less than what it would have been had the davitarm movement been truly circular about said rst pivot, whereby there isa smoothing-out of the movement of the davit arm head as the pivotalsupport for the arm changes from one pivot to the next. In other words,the sudden changes of direction and load which occur where the arc ofmovement about one pivot intercepts the arc of movement about anotherare smoothed out at least to a material extent. Thus, there is asubstantially steady load on the wire of the control winch or other gearinstead of a sharp change of load at the point of engagement of eachsucceeding pivot.

In a preferred embodiment of the invention a roller on the davit armengages a guideway or track on the stand or vice versa.

The invention will be further described, by way of example, withreference to the accompanying diagrammatic drawings which show oneembodiment of the invention as applied to a gravity davit of themultiple pivot type. On the drawings:

Figure 1 is a side elevation of the davit,

Figure 2 is a front elevation, and

Figure 3 is a fragmentary detail view of the guide means for the davitarm.

Briefly, the davit shown on the drawings comprises a stand I0. a davitarm II and a link I2.

2 .l One end of the link I2 is pivoted to the stand I0 at I3 (to providea iirst or upper fulcrum or pivoting device for the arm) and theotherend of the link is pivoted to the davit arm at I4 (to provide asecond or lower fulcrum or pivoting device for the arm). The arm IIcarries a keel chock or rest I5 which provides support for the boat b inthe stowed position. A stop'IS on the davit stand I0 arrests downwardand inboard movement of the link I2 at the end `of movement of the davitarm and link aboutthe rst fulcrum I3. A further stop-plate II haltsoutboard movement of the davit arm, about the fulcrum I4, at the finalextended position of the arm. The davit stand comprises two cheekplatessecured together in spaced-apart relationship and housing the davit armbetween them so as to provide good lateral support for the arm.

For the purpose of the present invention it is convenient to provide thelower forward part of the davit stand with an inclined or curvedtrackway or guide I8 and the davit arm with a roller I9 which isjournalled on a horizontal axle 20 on the arm in the neighbourhood ofthe keel f rest I5. In the launching operation, as the arm II and linkI2 tilt about the rst pivot I3 the roller I9 engages with the trackwayI8 and constrains the arm to move so that the path of movement of thedavit head I Ia is dened by the guideway I8 and not solely by theangular or circular movement of the link I2 about the pivot I3. Theinclination and length of the guideway I8 is such that there is nosudden dip and abrupt change of load as movement of the davit armchanges from that taking place about the first pivot I3 to that takingplace about the second or subsequent pivot I4. It will be noted that theinclination of the track I8 to the horizontal is less than that of thelink I2 when the latter is in its lowermost position. The roller mayleave the trackway some time before the arm completes its full outboardmovement. Successive positions of the roller I9 as it moves from thestowed position indicated at A to the fully outboard position indicatedat E are indicated at B, C and D and the corresponding positions of thedavit head IIa and second fulcrum I4 are similarly marked. Theapproximate path of movement of the davit head is indicated by the lineF. The line G indicates the truly circular path of movement of the davithead if the `track I8 and roller` 20 are omitted and it will be notedthat there is an adverse sudden change of direction at G. I.

To ensure outboard movement of the davit arm, even when the vessel onwhich the davit It will be appreciated that anlobv'ious mechanicalequivalent of the above described aring the inboard portion of itsmovement by the swinging of said link about said pivot means relative to4and outboard of said stop means and during the outboard portion of itsmovement by pivoting relative to said link while said link islstationary against said stop :"mearis, 'a 'roller on fsaid davit 'arm-`'and engageable with said track- Way to support said arm during theinboard por- -tion of its movement and while said'link is spacedrangement would be to have a roller 'or the "like on the stand arrangedto engage a 'cam-Sprole or track on the davit arm to constrain the headVof the latter to move in the required path.

In the stowed position the davit arm iii-lay rest directly or indirectlyon the upper face of Y the link I2 or on the upper pivot I3.

We claim:

,A gravity davit 'comprisinga davit stand having -a vdcwnwardly A:andoutwardly 'extending tramway, 'iixed 'pivot means at the upper 'portionlof said stand, a link pivotally suspended 'rom' said pivot `means, Aadavit arm "having a yd'avit head yat one fend 'and being pivoted at theother'end to the :lower free fend 'of said link, stop lmeans 7at thenlower portion or Asaid 'stand b'e'lowa'nd-o'i`1tb'c iard'of said pivotmeans "to limit iIibda'rd 'swinging df 'said link to Ja 'positionextending downwardly and outboard irom said p'ivot means, said davit armvbeing 'movable between "a lstowed Iinboard Yposition and 'an extended'outboard position vand vbeing guided dur- 'from said stop means,whereby tracking of said lrlleronnsaid trackvvay causes smoothtranslational movement. of-said arm during theswinging"6f"saidlink'rlative to said stop means and guides .thedavithead in a smooth path that is tangent tothe arc about the pivotbetween the *davit farm and lin-ll: when the link is stationary againstsaidfstop means.

WILLIAM EDWARD MORLEY. WALTER *GORDON MOORE.

lGreat Britain Sept. .19.1922'17

